var check_file = function(typ,pole,blad){
	var str=document.getElementById(pole).value.toUpperCase();
	var suffix=typ;
	
	if(!(str.indexOf(suffix, str.length - suffix.length) !== -1)){
		document.getElementById(pole).value='';
		document.getElementById(blad).style.display = "block";   
	}
	else
	{
		document.getElementById(blad).style.display = "none";
	}
}